The testes in humans must be maintained at a temperature below that of the rest of the body in order for sperm to mature. In fetal life they migrate out of the body cavity, through the inguinal canal to the scotal sac. When cold, the scrotal surface contracts in corrugations, supporting the testes close to the body. When warm, and in illness and the aged, the scrotum relaxes and the testes may hang uncomfortably low. Supporters that support the scrotum may also support the penis in some models. These generally employ straps that encircle the body and that may also pass between the legs to hold up the supporter. This construction is also characteristic of waterproof enclosures for male incontinence of urine. These multiple straps are awkward and uncomfortable to put in place and to wear.